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Is is-docker ESM-only? Can you require() it?

Check if the process is running inside a Docker container

Last verified Sep 9, 2026 against is-docker@4.0.0. Markdown · JSON

ESM-only ESM-only since 3.0.0 — last CommonJS version is 2.2.1

is-docker dropped its CommonJS build in 3.0.0 (August 2021). The last version with a plain require()-able CommonJS entry is 2.2.1, published Apr 9, 2021; it declares support for Node.js >=8.

On Node.js 20.19+, 22.12+ and newer, require("is-docker") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. Node.js 18 has no require(esm), and is-docker@4.0.0 declares Node.js >=20, so 18 is outside its supported range anyway.

is-docker@4.0.0 declares engines ">=20", so Node.js 18 is outside its supported range regardless of module format.

What to do

  1. On Node.js 20.19+, 22.12+ and newer, require("is-docker") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26.
  2. From a CommonJS file, use a dynamic import inside an async function: const isDocker = await import("is-docker"). That works on every Node.js version the package supports (>=20).
  3. If you need a synchronous require() or run Node.js 18: npm install is-docker@2.2.1, the last CommonJS release (published Apr 9, 2021); it declares Node.js >=8.
  4. is-docker@4.0.0 declares engines ">=20", so Node.js 18 is unsupported regardless: upgrade Node.js or pin an older release.
  5. TypeScript: types are bundled; install nothing extra.
Latest
4.0.0 (Sep 15, 2025)
Module format
ESM-only
Last CommonJS version
2.2.1
ESM-only since
3.0.0 (Aug 31, 2021)
TypeScript types
Bundled
Node engines
>=20
Weekly downloads
110.0M
License
MIT

Does is-docker@4.0.0 actually load? Runtime test results

Installed and executed on Sep 9, 2026 with require("is-docker") from a CommonJS file and import "is-docker" from an ES module.

Runtimerequire("is-docker")import "is-docker"
Node.js 18✗ failsERR_REQUIRE_ESM✓ works
Node.js 20✓ works✓ works
Node.js 22✓ works✓ works
Node.js 24✓ works✓ works
Node.js 26✓ works✓ works
Bun 1.4.0✓ works✓ works

How to import is-docker

ES modules (import)

import * as isDocker from "is-docker";

Namespace import shown because the ESM entry may have no default export; use named imports for what it exports.

CommonJS (require)

// Node.js 20.19+, 22.12+ and newer (verified):
const isDocker = require("is-docker");

// Any Node.js version the package supports (>=20), from an async function:
async function main() {
  const isDocker = await import("is-docker");
}

// Or pin the last CommonJS release (declares Node.js >=8):
// npm install is-docker@2.2.1

Module format by version

Derived from the type, main and exports fields of every stable release on npm, corrected where a runtime test of that version contradicted them (10 versions; the newest 10 shown).

VersionsFormatFirst published
3.0.0 – 4.0.0ESM-onlyAug 31, 2021
1.0.0 – 2.2.1CommonJSApr 8, 2015

Frequently asked

Is is-docker ESM-only?

is-docker@4.0.0 is ESM-only. is-docker dropped its CommonJS build in 3.0.0 (August 2021). The last version with a plain require()-able CommonJS entry is 2.2.1, published Apr 9, 2021; it declares support for Node.js >=8.

Which version of is-docker still supports CommonJS / require()?

2.2.1 is the last version of is-docker with a CommonJS build; it declares Node.js >=8. Install it with "npm install is-docker@2.2.1". Every version from 3.0.0 on is ESM-only.

How do I use is-docker from a CommonJS file?

From a CommonJS file, use a dynamic import inside an async function: const isDocker = await import("is-docker"). That works on every Node.js version the package supports (>=20). On Node.js 20.19+, 22.12+ and newer, require("is-docker") works with the latest version: Node.js loads synchronous ES modules through require(). Verified on Node.js 20, 22, 24 and 26. Alternatively pin is-docker@2.2.1 (declares Node.js >=8).

Does is-docker work in Bun?

Yes. import "is-docker" loaded successfully in Bun 1.4.0 on Sep 9, 2026.

Does is-docker ship TypeScript types?

Yes. is-docker bundles its own type declarations; no @types package is needed.

Links

Other esm-only packages

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